Who is the Beast?

From publisher blurb: An unlikely duo approach you in the tavern, a Dragon Born and a Drow, interrupting your down time. The propose a hunt to you, they are willing to pay good coin for a simple track and kill, returning the corpse for proof. Seems straight forward enough, except for the target a huge crab in the forest, an unlikely location. Should be easy money, assuming you can hunt and strike.